The present invention relates to a device for administering a substance, such as a drug or pharmaceutical agent, or withdrawing a substance transdermally to a patient. More particularly, the invention is directed to a device having an array of penetrating members and a method of manufacturing an array for delivering or removing a substance from a patient.
Various substances are extracted from or delivered to the body by many known processes. One method that is often used is the subcutaneous delivery using a needle or other cannula. The use of a needle cannula is an effective method of extracting or delivering a substance but is often painful to the patient. The pain typically experienced by the patient has prompted the development of alternative methods for extracting or delivering drugs.
Various devices have been proposed for introducing substances to the body by transdermal delivery methods. Transdermal delivery devices are often used to provide a sustained release of the drug to maintain a desired rate of delivery. Many transdermal delivery devices are not able to administer drugs at a sufficient rate to be used effectively. Moreover, many drugs can not be delivered transdermally since the drugs are not able to pass through the protective skin layers.
The skin is made up of several layers with the upper composite layer being the epithelial layer. The outermost layer of the skin is the stratum corneum that has well known barrier properties to prevent molecules and various substances from entering the body and analytes from exiting the body. The natural impermeability of the stratum corneum prevents the administration of most pharmaceutical agents and other substances through the skin. The stratum corneum is a complex structure of compacted keratinized cell remnants having a thickness of about 10-30 microns. The stratum corneum forms a waterproof membrane to protect the body from invasion by various substances and the outward migration of various compounds.
Numerous methods and devices have been proposed to enhance the permeability of the skin and to increase the diffusion of various substances through the skin to be utilized by the body. Typically, the delivery of drugs through the skin is enhanced by either increasing the permeability of the skin or increasing the force or energy used to direct the drug through the skin.
One example of a method for increasing the delivery of drugs through the skin is iontophoresis. Iontophoresis generally applies an external electrical field to ionize the drug, thereby increasing the diffusion of the drug through the skin. Iontophoresis can be difficult to control the amount and rate of drug delivery. Under some circumstances, iontophoresis can cause skin damage depending on the extent of ionization, the energy applied to ionize the drug and duration of the treatment.
In recent years there has been an increased interest in micro devices for delivering drugs through the skin is by forming micropores or cuts through the stratum corneum. By penetrating the stratum corneum and delivering the drug to the skin in or below the stratum corneum, many drugs can be effectively administered. The devices for penetrating the stratum corneum generally include a plurality of micron size needles or blades having a length to penetrate the stratum corneum without passing completely through the epidermis. Examples of these devices are disclosed in U.S. Pat. No. 5,879,326 to Godshall et al.; U.S. Pat. No. 5,250,023 to Lee et al., and WO 97/48440.
The micro devices that are commonly used are often manufactured using various techniques such as stereo lithography. These techniques can be used effectively to manufacture devices of a few microns and are able to form channels and other shapes for the delivery of fluids. A disadvantage of the devices is the cost of the manufacturing process and the time required to produce a single item. Other processes such as wet etching, plasma etching and machining can produce fine details in the finished substrate but are not cost or time effective for commercial use.
The prior manufacturing methods and devices for the transdermal administration of drugs have exhibited limited success. Accordingly, a continuing need exists in the industry for an improved device for the administration of various drugs and other substances.
The present invention is directed to a device for withdrawing or delivering a substance to a patient. In particular, the invention is directed to a method and apparatus for penetrating the skin to a sufficient depth where an analyte or other substance can be withdrawn or a pharmaceutical agent can be absorbed and utilized by the body. The invention is further directed to a method of manufacturing the device for withdrawing or delivering a substance to a patient.
Accordingly, a primary object of the invention is to provide a device for efficiently sampling or administering a substance transdermally through the skin substantially without pain to the patient.
Another object of the invention is to provide a device having a plurality of cannulas for penetrating the outer layers of the skin for withdrawing a sample or delivering a substance to the skin.
A further object of the invention is to provide a device for withdrawing a sample or delivering a substance. The device has a plurality of penetrating members in a support where the penetrating members have a distal end extending from the support a distance of about 50 microns to about 2 mm.
Another object of the invention is to provide a sampling or delivery device having a plurality of needles formed into an array in a substrate for penetrating the outer layers of the skin of a patient.
Still another object of the invention is to provide a sampling or delivery device having an array of needles extending from a support a distance of at least 100 microns for penetrating the skin.
Another object of the invention is to provide a device for sampling or delivering a substance having a plurality of cannulas with a length of about 100 to about 500 microns.
A further object of the invention is to provide a device for sampling or delivering a substance having a plurality of cannulas with a length of greater than 500 microns.
Another object of the invention is to provide a device for sampling or delivering a substance having a plurality of stainless steel cannulas.
These and other objects of the invention are substantially attained by providing a device for the intradermal withdrawing or delivery of a substance to a patient. The device comprises a support having a top end and a bottom end. The support has at least one channel extending from the top end to the bottom end. A skin penetrating member is positioned in the channel and is coupled to the support. The skin penetrating member has an exposed end extending from the bottom end of the support a distance sufficient to penetrate the skin of a patient.
The objects and advantages of the invention are further attained by providing a device for the intradermal withdrawing or delivery of a substance to a patient. The device comprises a support having an axial dimension with a top end and a bottom end and a plurality of spaced-apart axial channels extending from the top end to the bottom end. A skin penetrating member is positioned in each of the channels. Each of the skin penetrating members has a first end coupled to the housing and a second end extending axially from the bottom end of the support.
The objects of the invention are further attained by providing a method of manufacturing a skin penetrating device by the steps of providing a support having an axial dimension with a top end and a bottom end and a plurality of spaced apart channels extending from said bottom end in said axial dimension, and positioning a skin penetrating member in each of the axial channels, where the skin penetrating member has a first end coupled to the housing and a second end spaced from the bottom end.
The objects of the invention are still further attained by providing a method of forming a skin penetrating device comprising the steps of: providing a support having an axial dimension with a top end and a bottom end and at least one axial channel extending from the bottom end; and positioning a skin penetrating member completely in the axial channel and coupling the skin penetrating member to the support; and removing a portion of the bottom end of the support and exposing an end of the skin penetrating member.
The objects, advantages and other salient features of the invention will become apparent from the following detailed description which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the invention.